The most widely used nutritional intervention during pregnancy is the supplementation with iron and folic acid. As described in The Effect of High Folate Levels:What are the Findings , megaloblastic anemia, which frequently occurs during pregnancy, is believed to be caused by an inadequate intake of dietary folate. Iron deficiency has been indicated as an additional stress on folate metabolism and may be the actual cause of converting a sub clinical folate deficiency into a megaloblastic anemia. Because folic acid and iron deficiencies frequently coexist, routine administration of folic acid and iron in the form of a prenatal multivitamin capsule containing 65mg and 1mg respectively is suggested.
The best method for combating iron deficiency in pregnancy is to promote high intakes of available iron by the non-pregnant woman so that there will be at least 300mg of iron stored as she enters pregnancy.
Investigators have found an effective method of building up iron stores at the beginning of pregnancy. A single large dose of iron is injected early in pregnancy, which is said to protect against iron depletion throughout pregnancy. It is evident that iron supplementation is needed during pregnancy.
Infants are born with high hemoglobin levels of 18 to 22 g/dl of blood and have an iron store supply in the liver that will last from three to six months. During gestation the maternal organism transfers about 300mg of iron to the fetus. The fetus needs to grow and will require 70mg of iron for the placenta, 500mg for hemoglobin formation and 280mg to replace basal losses in hair, skin and sweat. The increase in maternal blood volume is as a result of the increase of 500mg for hemoglobin in the fetus. This represents almost twice the total iron reserves of the adult female. About 230mg of iron in the extra hemoglobin will be returned to the iron pools after delivery, when the blood volume returns to normal and a saving of 100 to 200 mg is effected by the absence of menstrual losses.
A 30% increase in red cells occurs during pregnancy and therefore a need for about 1mg of iron a day over and above the needs of the non-pregnant woman. If dietary iron is not available to meet this need either one of two impairments will occur. Firstly iron stores will be depleted and there will be a reduction in the expansion of red cell mass of the mother, rather than an impairment of fetal iron reserves. Secondly, if there are no iron reserves in the mother , maternal hemoglobin levels will drop. If these levels reach 10g/dl the pregnant woman will be considered anemic.
Elemental iron increases from 18mg to 27mg in the pregnant woman. Footnotes to RDA tables do state that this requirement cannot be met by ordinary diets. Administration of iron supplements is therefore highly recommended for all pregnant women and should be given in such a form as to minimize unpleasant gastrointestinal side effects
The most commonly used is ferrous sulphate, which is the least expensive and is quite well absorbed. It is important to note that iron may inhibit the absorption of other minerals and should be taken separately from supplements such as calcium. Adequate amounts of vitamin C however should be present to enhance the absorption of iron.
Resources:
1. Casaneuva E, Viteri FE. Nutrition as a Preventive Strategy Against Adverse Pregnancy Outcomes. Iron and Oxidative stress. J Nutr. 2003;133:1700.
2. Jackson AA, Bhutta ZA, Lumbiganon P. Nutrition as a Preventive Strategy Against Adverse Pregnancy Outcomes. J Nutr. 2003;133:1589s-1591s.
3. Halpern SL. Quick Reference to Clinical Nutrition. Toronto. J.B. Lippincott Company, 1989.
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